Fluid pressure operated telescopic hoists



Jan. 10, 1956 G. A. REA

FLUID PRESSURE OPERATED TELESCOPIC HOISTS 3 Sheets-Sheet 1 Filed July15, 1951 Jan. 10, 1956 Filed July 15, 1951 G. A. REA 2,730,401

FLUID PRESSURE OPERATED TELESCOPIC HOISTS 3 Sheets-Sheet 2 Jan. 10, 1956G. A. REA 2,730,401

FLUID PRESSURE OPERATED TELESCOPIC HOISTS Filed July 13, 1951 3Sheets-Sheet 3 INVEI% United t s atent 1 FLUID PRESSURE OPERATEDTELESCOPIC HOISTS George A. Rea, Pewaukee, Wis., assignor to The HellCo., Milwaukee, Wis., a corporation of Wisconsin This invention relatesto improvements in fluid pressure operated telescopic hoists.

Dumpingvehicles in which the dump body is movable froma load carryingposition to an over-balanced dumping position are particularly efiicientin discharging their loads, even sticky loads being freely dischargedbecause of the angularity of the dump body when in overbalanced dumpingposition. A dumping vehicle of this general type is shown in Patent No.2,047,051, issued on July 7, 1936, to George E. and Arthur P. Armington.

j With the above in mind it is a general object of the invention toprovide an improved fluid pressure operated telescopic hoist which isadapted for use in the overbalancing type of dumping vehicle, the fluidconduits .of the improved hoist being connected to a non-extensibleportion of said hoist.

A further object of the invention is to provide an improved multiplestage hoist of the class described having a double acting stage providedby the hoist cylinder and by the outermost sleeve within the cylinder,whereby extensile or retractile. movement of the hoist may beaccomplishedby introducing fluid under pressure into a selected end ofthe cylinder.

*A further object of the invention is to provide an improved hoist oftheclass described which is so constructed that the rate of extensilemovement thereof is restricted within safe limits even after thedumprbody has been overbalanced.

A further object of the invention is to provide an improved hoist of theclass described which is provided at each end with a' universal jointconnection to prevent binding of the movable parts of the hoist when thetruck frame is deflected due to uneven ground contours.

A further object of the invention is to provide an improvedh'oist 'ofthe class described which is strong and durable, relatively simple inconstruction, efficient in operation, and otherwise well adapted for thepurposes described.

With the above and other objects in view, the invention consists oftheimproved fluid pressure operated telescopic hoist, and all of itsparts and combinations, as set forth in the claims, and all equivalentsthereof.

- In the drawings accompanying and forming a part of this specification,wherein is shown one complete embodiment of the preferred form of theinvention, and wherein like characters of reference indicate the sameparts in all of the views:

Fig. 1 is a fragmentary side elevational view of an over balancing typeof dump truck having the improved hoist embodied therein, the overbalanced dumping position of the dump body and the corresponding fullyextendedposition of the hoist being shown in dot and dash lines;-

r Fig. 2 is an enlarged fragmentary bottom view of the improved hoisttaken approximately along the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary longitudinal sectional view taken approximatelyalong the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary view similar to Fig. 3 and showing the improvedhoist in fully extended position;

Fig. 5 is a diagrammatic view of the hydraulic circuit for actuating theimproved hoist, the control valve being disposed in body raisingposition;

Fig. 6 is a diagrammatic view of the control valve of Fig. 5, showingthe latter in body holding position; and

Fig. 7 is a view similar to Fig. 6 showing the control valve in bodylowering position.

Referring more particularly to Fig. 1 of the drawing, the numeral 10indicates a truck having longitudinally extending horizontal chassisrails 11 each provided at its rear end with an upstanding apertured lug12. A dump body 13 having a center of gravity positioned as at14 ispivoted at its rear end to the lugs 12 by pins 15. Fixed to a side rail11 is a depending bracket 16 which is formed at its lower end with atransversely extending bearing sleeve 17 clearly shown in Fig. 2. Asimilar bracket and bearing sleeve (not shown) may be correspondinglyfixed to the opposite frame side rail (also not shown). A shaft 18 ismounted in the bearingsleeve 17, and outwardly of said sleeve a block 19is freely rotatably mounted on the shaft 18 and is formed with a pair ofcoaxial oppositely directed stub shafts 20 and 21, the axis of which isnormal to the axis of the shaft 18. Outwardly of the block 19 the shaft18 is formed with a portion of reduced diameter 25 carrying a washer 22.A nut 23 is threaded onto the portion 25 for retaining the washer 22 andblock 19 in position. A locking screw 24 may extend transversely throughthe nut 23 and shaft portion 25 as shown in Fig. 3, and the screw 24 maybe provided with a lock nut 26.

Referring to Figs. 1 and 2, a pair of spaced depending brackets 27 ismounted on the underside of the dump body 13 above the bracket 16.'Fixed to the facing surfaces of the brackets 27 is a pair of bearingblocks 28 formed with transverse coaxial bores 29. A stub shaft 30 isrotatably positioned in each of the bores 29, and formed on each of thestub shafts 30 inwardly of its bearing block 28 is a rectangular bar 31which lies in a plane normal to the axis of its stub shaft 30. Spacedparallel transverse bars 32 connect corresponding opposite side edges ofthe bars 31 as shown in Figs. 2 and 3. The bars 32 are formed withcoaxial bores 33, the axis of which is normal to the axis of the stubshafts 30. A cylindrical pin 34 is positioned in and extends between thebores 33, and said pin may be retained in position by a'keeperplate 35which is welded to one end of the pin and is removably secured to theadjacent plate 32 by means of cap screws 36.

The improved hoist is provided with a cylinder 37 having an open endformed with an outwardly directed annular flange 38. The opposite closedend of the cylinder is formed with a pair of spaced parallellongitudinally extending lugs 39, to each of which a cap 41 isconnected, as by cap screws 40. The lugs 39 and their caps 41 are formedwith coaxial transverse bores 42 for rotatably receiving the stub shafts20 and 21 of the block 19, as shown in Figs. 1, 2 and 3. The improvedhoist is also formed with a piston rod 43 having its outer endformed'with an eye 44, and said eye is positioned between the plates 32with the pin 34 extending through its bore. It is apparent that thestructure so far described provides a universal joint connection betweenone end of the improved hoist and the frame of the truck 10, and it alsoprovides a universal joint connection between the other end of the imder37 and is smaller than said bore to provide an annular space 46 betweenthe sleeve and the wall of the bore 37 when the parts are disposed asshown in Fig. 3. A stop collar 47, which is threaded onto the inner endof the sleeve 45, has an annular flange portion 48 overlapping the endof said sleeve and projecting radially inwardly. The collar 47 carriesan annular bearing shell 49 which slidably engages the wall of thecylinder bore 37', and said collar also carries a piston ring 50 whichprovides positive sealing engagement between said collar and a cylinderwall.

The cylinder 37 is formed with a passage 51 which aftords communicationbetween the inner end of the cylinder bore 37' and the outer surface ofthe cylinder, there being a tubular connection 52 threaded into theouter terminus of the passage 51. The outer end of the bore 37 of thecylinder is formed with two annular portions 53 and 54 of enlargeddiameter. A passage 55 extends radially through the fiange 38 andaffords communication between the bore portion 53 and a tubularconnection member 56 which is threaded into the outer end of saidpassage. An annular collar 57 is bolted onto the flange 38 at the outerend of the cylinder and has an axially extending tubular portion 58formed on the inner end surface thereof and seated in the cylinder boreportion 54. The tubular portion 58 may be formed with a lug 58projecting axially from its inner end surface within the bore portion53. The collar 57 carries an annular bearing shell 59 which slidablyengages the outer surface of the sleeve 45. Above the shell 59 thecollar 57 is formed with an annular portion 60 of increased internaldiameter. Above the annular portion 60 the collar 57 is formed with athreaded portion 61 of still greater internal diameter. Surrounding thesleeve 45 within the portion 60 of the collar 57 is a packing 62 whichmay take the form of a plurality of sealing rings of suitable material.Threaded into the portion 61 of the collar 57 and compressibly engagingthe packing material 62 is a gland nut 63 for urging the packing intosealing engagement with the sleeve 45.

The sleeve 45 is formed with an internal annular shoulder 64 adjacentits outer end. Spaced outwardly from the shoulder 64 the sleeve 45 isformed with an internally threaded portion 65 of increased diameterwhich extends to the end of the sleeve. The shoulder 64 carries anannular bearing sleeve 66.

Positioned within the sleeve 45 and slidable in the hearing sleeve 66 isan inner sleeve 67 which is smaller in diameter than the sleeve 45 toform an annular space 68 when the sleeves are positioned as shown inFig. 3.

Threaded on the inner end of sleeve 67 is a stop collar 69 which isformed with an inwardly directed annular flange 70 overlapping the endof the sleeve 67 and projecting radially inwardly therefrom. The stopcollar 69 carries an annular bearing shell 71 which slidably engages theinner wall of the sleeve 45. The stop collar 69 is formed with anaxially extending passage extending the full length thereof. The annularflange 48 of the stop collar 47 is formed with a cutaway portion 81 toprovide communication between the inner end of the passage 80 and theinner end of the cylinder bore 37 when the parts are in the position ofFig. 3.

Surrounding the sleeve 67 outwardly of the shoulder 64 is a packing 72which may be formed of a plurality of packing rings of suitablematerial. A packing nut 73 is threaded into the portion 65 of the sleeve45 and urges said packing into sealing engagement with the sleeve 67.

The outer end of the sleeve 67 is internally threaded as at 74, andinwardly of the portion 74 the sleeve 67 is formed with a portion ofreduced diameter 75. Inwardly adjacent the portion 75 the sleeve 67 isformed with an internal annular shoulder 76 which carries an annularbearing shell 77. The piston rod 43 is normally positioned within thesleeve 67 and is axially slidable in the bearing shell 77, there beingan annular space 86 between the piston rod 43 and the sleeve 67 when theparts are positioned as shown in Fig. 3. Surrounding the piston rod 43within the portion 75 of the sleeve 67 is a suitable packing 78 whichmay also take the form of annular sealing rings, and threaded in theportion 74 of the sleeve 67 is a gland nut 79.

The inner end of the piston rod 43 is formed with an externally threadedportion 82 of reduced diameter which is formed with an axial recess 83.A pair of spaced axially extending passages 84 communicate between therecess 83 and a larger transverse passage 85 which opens through theside wall of the piston rod 43 and communicates with the annular space86 when the parts are positioned as shown in Fig. 3. Threaded on theportion 82 of the piston rod 43 is a cup-shaped piston 87 which carriesan annular bearing shell 88 for slidably engaging the inner wall of thesleeve 67. The piston 87 also carries a pair of spaced piston rings 89for sealingly engaging the wall of the sleeve 67. The closed end of thecup-shaped piston 87 is formed with an axial bore 90 which is providedat its inner end with an annular seat 91 for a ball check valve 92positioned within the recess 83. The end wall of the piston 87 is alsoformed with a restricted passage 93 which provides constantcommunication between the recess 83 and the inner end of the cylinderbore 37 Fig. 5 indicates diagrammatically a hydraulic control system foruse in operating the improved hoist. The numeral 94 indicates a fluidreservoir from which a positive displacement pump 95 is adapted to drawfluid through a conduit 96. A control valve 97 may be of the disk type,having a rotatable disk valve 98 positioned within a valve body 99. Thevalve body 99 may be formed with a port 100 which communicates with theoutlet of the pump 95 through a conduit 101. The valve body 99 may alsobe formed with a pair of ports 102 and 103, each offset 90 degrees fromthe port 100. The port 102 communicates with the tubular connection 52on the cylinder 37, as shown, and the port 103 communicates with thetubular connection 56 on the cylinder 37, as shown. The valve member 98may be formed with an axial bore 104, and affording communicationbetween said bore and the reservoir 94 is a conduit 105. A check valve106 provides one-way communication between the conduits and 56 as shown,and a pressure relief valve 107 is connected between the conduits 101and 105.

The valve member 98 may be formed with a peripheral groove 108 which ispreferably substantially greater than 90 degrees but less than 180degrees in extent, the groove 108 being so positioned that it is adaptedto communicate with the ports 100, 102 and 103 in various positions.Offset approximately 90 degrees from one end of the peripheral groove108 is a relatively short peripheral groove 109 which is positioned inthe same plane with the groove 108. A radial passage 110 affordscommunication between the groove 109 and the axial bore 104 of the valvemember.

In order to raise the truck body 13 from the stable load carryingposition shown in solid lines in Fig. l to the over-balanced dumpingposition shown in dot and dash lines in Fig. l, the valve member 98 ofthe valve 97 is turned to the position shown in Fig. 5. The pump 95 thendraws fluid from the reservoir 94 and delivers it under pressure throughthe valve port 100, groove 108, port 102, and tubular connection 52, tothe inner end of the cylinder bore 37. Referring to Fig. 3 this causesthe sleeves 45 and 67 and the piston 87 and its rod 43 to move outwardlyas a unit until the stop collar 47 of the sleeve 45 abuts the lug 58 ofthe collar 57. The lug 58 holds the collar 47 spaced from the portion 59of the collar 57, as shown in Fig. 4. During this outward movement ofthe collar 47 and sleeve 45 fluid within the annular space 46 is forcedout through the passage 55 and into the connection 56 from which inderbore 37 through the passage 30 in the collar 69.

The piston 87 and rod 43 continue to move outwardly under the force ofthe fluid pressure until the piston abuts the shoulder 76 of the sleeve67. Since the hoist when fully extended can accommodate no morehydraulic fluid, any further fluid pumped into the conduit 101 by thepump 95 will bypass back to the reservoir 94 throughthe pressure reliefvalve 107 and conduit 105.

As the piston 87 moves outwardly within the sleeve 67, the center ofgravity 14 of the truck body 13 passes from a position on the forwardside of the axis of the pin to the position shown by dot and dash linesin Fig. 1 where the center of gravity is rearwardly of the axis'of thepivot pin 15.

As the piston 87 moves outwardly within the sleeve 67, the fluid fromthe annular space 86 is forced out through the passage 85, passages 84,recess 83 and restricted passage 93 into the inner end of the cylinderbore 37'. Due to the restricted size of the passage 93, the escape offluid from the space 86 is limited, and

.the speed of outward movement of the piston 37, relative to the sleeve67 is also limited as a result. This provides a dash-pot snubbing actionand prevents the piston from being pulled outwardly at excessive speedby the overbalanced pump body 13. Limiting the speed of movement of thepiston 87 in this manner lessens the shock on the mechanism when thereis an abrupt stoppage of the piston at its outer limit of travel as itengages the shoulder 76. Excessive stresses on the mechanism are therebyprevented.

To hold the body 13 in overbalanced pumping position, the valve member93 is turned to the position shown in Fig. 6. In this position the valveprevents flow of fluid to or from the cylinder 37 through the tubularconnections 52 and 56. Fluid pumped into the port 100 by the pump 95then flows through the passage 110, bore 104 and back to the reservoir94 through the conduit 105.

To lower the body 13 from raised position, the valve member 98 is turnedto the position shown in Fig. 7. Fluid under pressure from the pump 95flows from the conduit 101 through the port 100, groove 108, port 103,tubular connection 56 and passage 55 into the annular recess 53 as wellas into the annular space between the end of the collar 47 and theadjacent end of the tubular extension 58. The fluid pressure forces thecollar 47 inwardly along the cylinder bore 37 and said collar pulls withit the sleeves 45 and 67 as well as the piston 86, piston rod 43 anddump body 13. Fluid escapes from the inner end of the cylinder bore 37through the passage 51 and tubular connection 52, and flows through thevalve port 102, groove 109, radial passage 110, axial bore 104 and backto the reservoir 94 through the conduit 105. When the collar 47 reachesthe retracted position shown in Fig. 3, the annular space 46 canaccommodate no more fluid. Therefore any fluid delivered to the conduit101 by the pump 95 will bypass to the reservoir 94 through the pressurerelief valve 107 and conduit 105.

As the collar 47 moves from the extended position of Fig. 4 back towardthe retracted position of Fig. 3, the dump body 13 is pulled forwardlyfrom overbalanced position to a position where the center of gravity 14is forwardly of the axis of the pivot pin 15. In this position theweight of the body 13 pushes inwardly on the piston rod 43 to cause thepiston 87 to move inwardly along the sleeve 67, as well as to cause thesleeve 67 to move inwardly along the sleeve 45. As the piston 87 movesinwardly along the sleeve 67, fluid flows freely from the inner end ofthe cylinder bore 37 through the passage 90, past ball 92, throughrecess 83, passages 84 and 85, into the annular space 86. As the sleeve67 moves inwardly, fluid from the inner end of the cylinder bore 37'flows into the annular space 68 through the re stricted passage in thecollar 69. By again turning the valve 98 to the position of Fig. 6, theconduits 52 and 56 are sealed off to lock the hoist in retractedposition, and the fluid from the pump is pumped directly to thereservoir 94 through the conduits 101 and 105 without passing throughthe relief valve 107.

Various changes and modifications may be made without departing from thespirit of the invention, and all of such changes are contemplated as maycome within the scope of the claims.

What I claim as the invention is:

1. In a fluid operated ram for use in a vehicle having a dump bodymounted thereon for movement between a load carrying position and anoverbalanced dumping position: a sleeve having an inner and an outerend; means for introducing fluid under pressure into the inner end ofsaid sleeve; a piston axially slidable in said sleeve; a piston rod ofsmaller diameter than said sleeve projecting through the outer end ofsaid sleeve; means forming a seal between said piston rod and the outerend of said sleeve; a restricted passage affording constantcommunication between the fluid spaces in said sleeve on opposite sidesof said piston; a passage of relatively large crosssection connectingthe fluid spaces on opposite sides of said piston; and a check valve inthe latter passage permitting fluid flow through said relatively largepassage only during retracting movement of said piston.

2. In a fluid operated ram for use in a vehicle having a dump bodymounted thereon for movement between a load carrying position and anoverbalanced dumping position: a cylinder having a closed inner end witha fluid spaced thereover and having an open outer end; at least oneconcentric open ended sleeve axially slidable within said cylinder andslidably projecting from the open outer end thereof; means forming aseal between said sleeve and the outer end of said cylinder; a pistonaxially slidable within said sleeve; a piston rod for said pistonprojecting from the outer end of said sleeve and having a diametersmaller than the inner diameter of said sleeve to provide an annularfluid space therebetween; means providing a seal between said piston rodand the outer end of said sleeve; means limiting the extensile movementof said sleeve relative to said cylinder; and means for introducingfluid under pressure into the inner end of said cylinder; said pistonbeing formed with a restricted passage affording only limitedcommunication between said fluid space below the piston adjacent theclosed inner end of the cylinder and the fluid space between said pistonrod and sleeve whereby a special snubbing action takes place only duringextensile movement of said piston relative to said sleeve, said snubbingbeing elfective substantially throughout the length of movement of saidpiston relative to said sleeve.

3. In a fluid operated ram for use in a vehicle having a dump bodymounted thereon for movement between a load carrying position and anoverbalanced dumping position: a cylinder having a closed inner end andan open outer end; at least one concentric open ended sleeve axiallyslidable within said cylinder and slidably projecting from the openouter end thereof; means forming a seal between said sleeve and theouter end of said cylinder; a piston axially slidable within saidsleeve; a piston rod for said piston projecting from the outer end ofsaid sleeve and having a diameter smaller than the inner diameter ofsaid sleeve to provide an annular fluid space therebetween; meansproviding a seal between said piston rod and the outer end of saidsleeve; means limiting the extensile movement of said sleeve relative tosaid cylinder; and means for introducing fluid under pressure into theinner end of said cylinder; means forming a restricted passage affordingcommunication between the inner end of the cylinder and the fluid spacebetween said piston rod and sleeve for limiting the rate of extensilemovement of said piston and rod relative to said sleeve; means forming apassage of relatively large cross-section affording communicationbetween the inner end of the cylinder and the fluid space between thepiston rod and sleeve; and a check valve in the latter passagepermitting fluid flow through said latter passage only during retractilemovement of the piston.

4. In a vehicle having a frame, having a dump body mounted thereon andmovable between a load carrying position and an overbalanced dumpingposition, and having a fluid operated ram for actuating said dump body,said ram comprising: a sleeve having an inner end with a fluid space,said space being connected to said frame and having an outer end; apiston axially slidable in said sleeve; a piston rod of smaller diameterthan said sleeve projecting from the outer end of said sleeve andconnected to said dump body, there being a fluid space between saidpiston rod and said sleeve outwardly of the piston; means forming a sealbetween said piston rod and the outer end of the sleeve; means forintroducing fluid under pressure into the inner end of said sleeve tocause extensile movement of the piston relative to the sleeve, said rambeing connected to said frame and dump body in such a manner that thedump body is moved to overbalanced condition by extensile movement ofthe piston to a predetermined position spaced from the outer end of saidsleeve; and means forming a restricted passage affording only limitedcommunication between the fluid space below the piston adjacent theinner end of said sleeve and the fluid space between said piston rod andsleeve whereby a special snubbing action takes place after said body hasbecome overbalanced said snubbing action being effective substantiallythroughout the length of travel of said piston relative to said sleeveand only during extensile movement thereof.

5. In a vehicle having a frame, having a dump body mounted thereon andmovable between a load carrying position and an overbalanced dumpingposition, and having a fluid operated ram for actuating said dump body,said ram comprising: a sleeve having an inner end connected to saidframe and having an outer end; a piston axially slidable in said sleeve;a piston rod of smaller diameter than said sleeve projecting from theouter end of said sleeve and connected to said dump body, there beingfluid space between said piston rod and said sleeve outwardly of thepiston; means forming a seal between said piston rod and the outer endof the sleeve; means for introducing fluid under pressure into the innerend of said sleeve to cause extensile movement of the piston relative tothe sleeve, said ram being connected to said frame and dump body in sucha manner that the dump body is moved to overbaianccd condition byextensile movement of the piston to a predetermined position spaced fromthe outer end of said sleeve, means forming a restricted passageaffording communication between the inner end of said sieeve and thefluid space between said piston rod and sleeve for limiting the rate ofextensile travel of the piston after said body has become overbalanced;means forming a passage of relatively large cross-section affordingcommunication between said fluid space and the inner end of the sleeve;and a check valve in the latter passage permitting iuid flow throughsaid relatively large passage only during retractile movement of thepiston.

References Cited in the file of this patent UNITED STATES PATENTS Re.17,130 Berry Nov. 13, 1928 1,465,365 Ross Aug. 21, 1923 1,925,296Barrett Sept. 5, 1933 2,517,153 Wood Aug. 1, 1950 2,590,362 Bennett Mar.25, 1952 FOREIGN PATENTS 552,087 France Jan. 17, 1923

